242 PASSALID^. 



clypeus separated by a suture from the front. Aiitennse with, 

 three- jointed ehib. INIandibles usually without movable 

 tooth. Maxilla with the imier lobe two-pronged. Labium 

 not broad, the ligula sharply pointed, not enclosed by the 

 mentum, labial palpi not dilated, the last jomt long. Front 

 coxae not embedded, very prominent, contiguous, not separated 

 by the prosternum. Middle tibia armed externally, with one 

 or more shaq) sjjines, not hairy. 



Key to the Genera of Aulacocyclin^. 



Head flat in front ; mandibles without 



process Aulacocyclus Kaup., p. 242. 



Head bearing frontal horn ; mandibles 



with erect frontal process Ceracupes Kaup., p. 244. 



Genus AULACOCYCLUS. 



Aulacocyclus Kaup, Col. Hefte iii, 1868, p. 4 ; Gravely, Mem. Ind. 



Mus. iii, 1914, p. 193 ; Dibb, Stvlops, i, 1932. p. 257 ; Ent. Mon. 



Mag. Ixix, 1933, p. 197. 

 Txniocerus Kaup, Berl. Ent. Zeitschr. xv, 1871, suppl., p. 20. 



Type, Passalus edentulus Macl. (Australia). 



Range. Southern India, the Indo-Malayan and Papuan 

 Regions, and Australia. 



Body narrow, cylmdrieal, not flattened, very smooth and 

 shining, almost naked, the legs with very scanty hair, the 

 middle tibia armed with a sharp lateral spine. Front margm 

 of head without projections, bordered by a marginal groove, 

 the vertex bearmg a median process, sometimes bent and 

 directed forward at its extremity. Pronotum completely 

 margined and bearmg a deep longitudinal median groove. 

 Elytra deeply sulcate. Antemial club composed of three 

 lamella^, the three preceding joints not produced. Mandible 

 without movable tooth and ^^ith erect lateral process. Maxilla 

 with the inner lobe composed of two prongs. Labium long, 

 the ligula not enclosed by the lateral lobes on the mentum, 

 trilobed at the end, the middle lobe acutely pointed, the labial 

 palpi not dilated, the terminal joint long. 



Those forms, which, like A. bicKspis, have not the central 

 process of the head produced and hooked at the end, have been 

 regarded as forming a separate genus, Tii^niocerus, but Dibb 

 has pointed out that the transition from one form to the other 

 is unbroken. He has regarded the shape of the lateral scar of 

 the pronotum, simple in Aulacocyclus and branching in 

 Tsenioc4>,rus, as a distmctive feature, but this also fails, for the 

 scar is extremely simple in .4. devrollei, which cannot be 

 excluded from Tcvniocerus, if that name is to be retained. 



